To provide all countries with clean energy and deliver it anywhere in the world, solar panels can do it all, according to experts and scientists around the world.
Only 1.11% of global energy consumption in 2019 came from solar power. The sun has enormous energy potential, so researchers are looking for a way to make the best use of all its possibilities.
At first glance, solar energy is a simple and obvious choice. Unlike fossil fuels, it produces no greenhouse gases that accelerate global warming. Competition for water resources and territories is also not a problem.
Even politically, solar energy is one of the safest sources of alternative energy. There have been major conflicts over the right to dispose of oil and coal reserves. In this sense, solar energy is universal – it belongs to everyone and to no one at the same time.
Why isn’t it efficient to get solar energy on Earth?
According to NASA, about 29% of solar energy is reflected back from the Earth’s atmosphere and dissipated into space. On top of that, another 23% of solar energy is absorbed by water vapor, ozone and dust as it passes through the atmosphere. In the end, only 48% of solar energy reaches our planet.
Therefore, solar panels on Earth receive at best half of the original amount of energy. But there is also a problem with the batteries themselves, their maximum efficiency is about 22%: we are talking about non-laboratory conditions. And most importantly, solar panels work only during daylight hours. So there is an idea to get energy directly from the Sun, without being on Earth.
How does cosmic solar energy work?
Space solar power (SBSP) is the idea of collecting solar energy in space using satellite solar panels. It is then transmitted wirelessly to Earth. According to the European Space Agency (ESA), light from the Sun outside the atmosphere is 11 times more intense. Therefore, satellite solar panels can provide a huge amount of energy that mankind cannot even spend.
In addition, satellite panels are not threatened by bad weather and sunset. From space, these devices will be able to transmit energy to anywhere on Earth, so you only need to put the satellites in an optimal orbit.
How to deploy a solar panel in space?
To make space solar power available, two basic technologies are needed. First, launch vehicles to carry materials into space must be inexpensive and environmentally friendly. Most of the rockets currently used to deliver payloads are very expensive and polluting. Several private companies, such as SpaceX, are now developing cheap reusable rockets.
The second point is the construction of solar satellites in orbit. In order to collect the necessary amount of energy, the satellite solar panels would have to be much larger than the ISS. In fact, it would be a huge spacecraft. On the other hand, space panels are easier to assemble than the ISS.
What are solar satellites like?
According to researchers at the U.S. Department of Energy, there are two types of satellites that could be built to collect space power. Both of these types would consist of solar collectors, reflectors and a transmitter. Reflectors are large mirrors that would direct radiation to small panels – collectors – then the latter would convert the solar energy into microwave energy or into a laser to transmit it to Earth. Receiving stations on Earth would collect, store, and distribute the energy.
Microwave transmission satellites
The larger of the two designs would be microwave transmitting satellites. They would be made of huge solar reflectors that direct solar energy to the center of the satellite, from where it is then transmitted to Earth in the form of microwaves. Satellites transmitting microwave signals will orbit the Earth in a geostationary orbit at an altitude of about 35,000 kilometers – just under one-tenth the distance to the Moon.
Nevertheless, all such structures would be enormous. The solar reflectors alone will weigh more than 80,000 metric tons with diameters up to 3 kilometers. Due to their enormous size, satellites transmitting microwave signals will be able to generate gigawatts of energy and power large cities of the world. In addition, the wavelength of the electromagnetic spectrum is relatively long, so the transmission of energy from such a satellite will be as fast and intense as sunlight reaches the Earth.
Launching, assembling, and operating microwave transmitting satellites is all very expensive. Their cost is estimated at tens of billions of dollars. Because of their large size, it would take 40 to 100 launches to deliver all the materials. In addition, the size of receiving centers on Earth must be scalable to the size of satellites in space – about 3 to 10 km in diameter. And such large areas of land are difficult to master and maintain.
Satellites with laser transmission
The second type of solar satellites are laser-transmission satellites – they will only be about 2 m in diameter. They will contain an alkaline diode-pumped laser to transmit energy back to Earth. The laser could be about the size of a kitchen table and emit energy back to Earth with more than 50% efficiency.
Laser-pumped satellites will be launched in groups into low Earth orbit (LEO) at about 400 km, since they are small in size. Production of such devices is less risky and requires less time compared to microwave transmitting satellites. Cost estimates for laser-transmitting satellites range from $500 million to $1 billion.
But there are downsides as well. Laser-transmitting satellites are less powerful: each unit will generate only 1 to 10 MW of power. Even if you launch many units at once, they can’t match the power that microwave transmission satellites provide. And since the power is lower, it will be harder to transmit power through heavy clouds and rain.
Launching solar panels into space would help solve not only energy problems, but also social and political conflicts. Many countries are currently dependent on fossil fuel supplies, and limited supplies of oil and carbon are causing serious international conflicts. Solar energy will help ensure energy independence. Also, this energy can be exported to almost anywhere in the world.
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